Memories, such as flash memories, are used for storing a variety of data. Often, it is desirable to protect a portion of the memory from being changed. Typically, the portion of the memory is protected from being modified using conventional software protection or conventional hardware protection. If conventional software protection is used, then protect, unprotect, and lock-down commands are provided. The protect commands allows the portion of the memory to be protected from any modification. The unprotect command allows the portion of the memory to be modified. The lock-down command precludes changing the portion of the memory. If conventional hardware protection is provided, then a dedicated pad is typically provided. In most such conventional systems, when the dedicated pad is tied to ground, the portion of the memory is protected. In some conventional memories, a particular portion of the memory is pre-selected for protection.
Although the conventional software and hardware protection systems function, one of ordinary skill in the art will readily recognize that each has drawbacks. Although conventional software protection allows the protection of the portion of the memory to be dynamically changed, the protection is volatile. Consequently, once power to the memory is shut off, the protection is lost. Conventional hardware protection is nonvolatile. However, one of ordinary skill in the art will readily recognize that tying the dedicated pad to ground precludes any modification of the device. Conventional systems do exist which allow a particular block of the memory to be protected from programming in a nonvolatile fashion. However, such conventional mechanisms for providing nonvolatile protection against programming still have drawbacks such as the inability to configure the size of the portion of the memory being protected or the inability to choose the address position of the portion of the memory to be protected.
Accordingly, what is needed is an improved nonvolatile method and system for protecting memories from being modified. The present invention addresses such a need.